1. Field of the Invention
The present invention relates to an electronic calculator, display method, and recording medium for displaying a mathematical expression in full color.
2. Description of Related Art
There is conventionally known, as an electronic calculator (electronic desk calculator) which executes calculations of various input mathematical expressions and displays calculation results, a scientific electronic calculator which can perform a calculation using a logarithm function or the like in addition to four arithmetic operations.
In the scientific electronic calculator, formats for displaying the input mathematical expression include a format (linear display format) which displays in line numbers and signs constituting the mathematical expression, and a format (natural display format) which displays the mathematical expression in an arithmetic manner shown in a general textbook, book, and the like. For example, in a case of representing the second power of “a”, the linear display format displays “a^2”, while the natural display format displays “a2”.
In the natural display format, displaying numbers and characters in view of a vertical arrangement is referred to as a 2D (dimension) display, and a function such as root “√”, fraction “a/b”, or exponential notation “mn” which requires the 2D display is referred to as a 2D function.
There is known Japanese Patent Application Laid-Open No. 2007-264765 as a disclosure of a technique to appropriately control a cursor movement in a mathematical expression in the scientific electronic calculator employing the natural display format.
However, when an exponent of an exponentiation calculation is input in the scientific electronic calculator employing the natural display format, it is difficult to distinguish a display line on which a numeric value (base) to be raised is displayed, from a display line on which the exponent (index) is displayed, if the characters in these display lines are displayed in the same color. In addition, in a case where a radical sign further contains a radical sign like a multiple roots expression and the radical sign and numeric value provided in the inner side and the radical sign and numeric value provided in the outer side are displayed in the same color, or in a case where “×” serving as a multiplication sign is omitted between an integral part and a fraction in a mixed fraction, it is difficult for a user to distinguish each component in the mathematical expression if they are all displayed in the same color. Especially, it is difficult to distinguish where the cursor belongs when the 2D function is used.